Water tube boiler



'CCL 27, 1931.. R v s THRY 1,829,1 19

WATER TUBE BOILER Filed Dec. l5, 1928 ATM/WH Patented Oct. 27, 1931 UNITED STATES -PATENT OFFICE REN VICTOR STANISLAS THRY, OF ST. NAZAIRE, FRANCE, ASSIGNOR TO COMPAGNIE DE FIVES-LILLE, OF PARIS, FRANCE, A FRENCH COMPANY WATER TUBE BOILER' Application led December 13, 1928, Serial No. 325,872, and in France December 19, 1927.V

This invention has reference to activating an exchange of calories between liquid contained in a tube and the tube-surrounding medium; and it relates more particularly to water-tube boilers and especially those of the tubes therein that are directly exposed to reboX radiation.

As persons skilled in the art are aware, such tubes take up a relatively considerable portion of the heat from the re-box. Vaporization is intensive therein, and scales show a marked tendency to deposit in these parts, resulting in rapid wear. On the other hand their heat absorbing capacity is frequently limited by the formation of an insulating film of steam on their walls.

My invention has for its purpose to do away with the above set forth drawbacks.

The invention consists essentially, on the one hand, in accelerating circula-tion through the tubes concerned by applying an eXtra impulse to their water contents, and, on the other hand, in applying said impulse under pulsatory form so as to impart to the water within the tubes a jerky motion the mean velocity of which is other than zero, thereby reproducing the well known advantages that vaccrue to locomotives from the rail-track jolts.

In order to make my invention more clearly understood I have illustrated, as an example, an embodiment thereof and by drawings appended hereto and wherein:

Figure l is a view in longitudinal section of a boiler header fitted with the device according to my invention;

Figure 2 is an enlarged cross section of the same.

From the lower header 1 of the boiler starts 40 the nest of tubes composed, in the case shown,

of two rows 2 and 3 of tubes arranged respectively in quincunX fashion.

Opposite the outlet of said tubes 2 and 3, a pipe 4t is arranged within the header parallel to the axis of header 1, said pipe 4 being fitted with a multiplicity of small nipples or jets 5, each of them located in line with the axis of one of the tubes 2 or 8.

Pipe 4 is connected with the delivery side of a pump 6, the suction side of which is connected with header l itself (Figure l). Said pump 6 is so designed that it will have a pulsatory forcing pressure the mean value of which is other than zero. Such pulsations may be obtained with sutlicient frequency by using a rotary pump driven at suitable speed, owing to the separating action that takes place on the suction side ,between thevpum'p blades and the sucked-in water loaded with steam bubbles.` Infact, the'velocity ofthe moving fluid sometimes becomes less than the speed of the pump wheel because of the viscosity or because of the resistance of the intake pipe. A plunger pump may also be used having a reduced number of cylinders and devoid of the usual pulsation-damping a1r reservolr.

' In operation, the nipples or jets 5 do duty as injectors. The water circulation velocity throughthe tubes is considerably increased beyond normalcirculationvelocity, and this high velocity already fosters rapid steam ex haust, while increasing the absorption power of the tubes. At the same time, the pulsations caused by pump 6 maintain within the tubes of vibratory condition calculated to prevent the formation of deposits and to op-` pose` any film formation effect (that is to say the occurence o f a stagnant water or steam layer along the walls of the tube, which layer hinders heat transmission).

It may be found desirable or advantageous to control the pulsating apparatus in such manner as to further insure consonance ,between the pulsations thereof and those of the tubes themselves, that is, to attune the vibrations artificially produced with those inherent in the corresponding tubes.

It should be noted that the above described device in no way hinders ordinary circulation, thereby permitting the pump to be thrown out of operation at slow speeds and, on the other hand, constituting an important advantage as to safety in the event of the pump happening to be accidentally thrown out of commission in the course of operation.

I wish it to be clearly understood that my invention is not limited to the above described embodiment of al pulsatory circulation, although said embodiment has proven Sil gli

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advantageous on account f its simplicity and of its safety. It might, however, be replaced by any other device calculated to env sure equivalent results, or also, circulation might just be yactivated Without any pulsations being produced Furthermore, although I 'have described my invention as appliedto a Water-tube boiler and more speciallyas applied to tubes so called overheating, that is to say directly exposed to fire-boxl radiation, itlnay be ad?y f' vantageously applied to any heat eXchangery comprising tubestraversedby a liquid.v

' Havingnowparticularly -ascertained andV described the nature of my said invention as Welly asthe manner Vin* 'which the same is :to beperfonmedlideclare that what I claim is:

L A method ofpreventngscale forma- 'i f tion fand improving fthe operation of-a Water tube boiler for.4 like Y heat-exchanging apparatus,reonsi's'tingin-i-njefctingjetpulsationsof Water into the tubes ofthefboiler'toeimpart a pulsating motion to ,the wateralready inthe tubes in the direction of normal circulation, suchymotion having -a 'meanV velocity other than zero, andthe pulsations ,imparted -to the water in the tubes being in consonance with the vibration oftlietubes. Y t2. ln aVWater-.tube boiler =or lileiapparatus comprising upper andl lowerv headers, and a nest `of WaterA tubes",conneatingl the headers and opening into the same at opposite rends; a `Water delivery pipe having its' major portion disposed within .the .lower header adjacent Ythe points Wherethe lower endsof the tubes open rthereinto,.said Tpipe,beingpro-jk .Y

vided with a multiplicity `0;f nipples arranged illzaxallalinement with said-tube yend-s to-inl jectdirectly into fthemfjet pulsations of 'Waten; a pump lexternal to tsaidheader and lto 'A the delivery side #of which fsaid epipe `is eon, nected; andra; supply ,pipe opening/,at one-end into th'e'h'eader n'and having its other end connec-ted to thesuctionside'ofthe puinpftordraw water intofthe .latter 'from the header when the pump is in operation, the trefquency `of pulsation .of the Ipump corresponding With thevnatural period of vibrationfof Vthe ,tubes to revent xthe formation ilof scale deposit wit :inthetubes.I` l y v v .In1testiniony 'whereof .I faix .my signature 

